Efflorescence

 

I have recently been asked give my advice on how to stop efflorescence (salt deposits) re- occurring on the external walls of a property in Orba. The owners of the property keep washing it off only to find it returns shortly afterwards.

Firstly I need to explain what efflorescence is and what it looks like.
Efflorescence is formed by water within porous building materials, for example concrete, brickwork, stone and render etc. reacting with the natural salts contained within them. These salts dissolve in the water and are carried to, and deposited on the surface, by the natural evaporation that occurs by air coming into contact with the surface of the wall.


Under normal circumstances this white fluffy powdery efflorescent salt seen on the surface occurs in relatively new buildings because the brickwork or block work was not protected during construction and has become very wet. Normally in new buildings the salts can be brushed off and should not re-occur. However if the problem is re-occurring time after time as in this case, it is because water is being allowed to continuously enter the construction material and efflorescence will continue to form.


In this situation the cause must be found and eradicated, efflorescence is mainly seen on the lower sections of  walls and the most common cause is rising damp; this is where porous building materials act like a sponge, soaking up the ground water by what is known as capillary attraction.  This is usually because there is an absence of a damp proof course (d.p.c.) and quite common in Spanish properties. In this situation it would be wise to install a d.p.c. therefore stopping the water from rising up the walls. There is a treatment for efflorescence, a salt neutraliser, however this should only be used after the cause has been eliminated and will only be successful if no more water is passing through the wall. This salt neutraliser can only be applied to bare plaster, render, stone or brickwork. – it will not pass through paint.


Once you are sure you have stopped the problem of water entering into the fabric of the building the most effective treatment for efflorescence on external surfaces is time. The natural weathering of the surface, if maintained, will remove it. For a build up of deposits on a wall, a good scrub with a dry stiff brush will remove the worst, but make sure you follow it with a soft brush to move the salts away from the wall entirely as they will stay in the pores of the brickwork and dissolve again when it is wet.


John Phillips (F.I.A.S. F.A.B.E. M.I.B.C.O. F.F.B. M.R.S.H. C.M.W.O.B.O. M.B.I.M)
Construction Buena Vista

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Buena Vista Villas s.l.

Urb. Palmeria. Orba 03790

 

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